This invention relates generally to can bodymaking equipment and in particular relates to stripping of newly formed can bodies from the ram that drives the can forming blank through the forming dies.
In the art of bodymaking apparatus for transforming blanks in the form of relatively short metal cups into elongated bodies for two piece cans, the bodies are stripped from the ram by mechanical devices that engage the edge at the open end of the body and/or by utilizing compressed air that enters the can body through one or more outlets at the downstream end of the ram. Mechanical strippers by themselves have been found to be unreliable, especially at high production speeds. Problems have also arisen at high production speeds when application of compressed air for stripping is under the control of valves that are mounted in the ram at its downstream end to be actuated by sensing that formation of the can body base profile has been completed. The prior art has also controlled application of compressed air for stripping by utilizing solenoid actuated valves that are mounted on the machine frame in a stationary position. Because solenoid valves are relatively slow to recycle, it is difficult to meet high cycle rate requirements. Air-line supply contaminates add to this problem. While solenoid valves can be shielded from much machine vibration, the total effect of slow recycling and contaminates is that solenoid valve operation becomes erratic at high cycle rates, making it difficult to maintain, adjust and/or control coordination between the position of the ram and the application of compressed air for stripping.
Examples of can body strippers are disclosed in U.S. Pat. No. 3,524,338 issued Aug. 18, 1970 to J. S. Bozek for A Stripping Punch; U.S. Pat. No. 3,572,271 issued Mar. 23, 1971 to E. C. Fraze for Fabrication Of Can Bodies With Integral Bottom Walls; U.S. Pat. No. 3,771,344 issued Nov. 13, 1973 to G. W. Wright for Apparatus For Stripping Container Bodies From Metal Working Punches; and U.S. Pat. No. 5,056,350 issued Oct. 15, 1991 to B. A. Moen, W. R. Williams, B. E. Johansson and L. W. Mayer for Apparatus And Method For Stripping A Workpiece From Supporting Device.